The fouling phenomenon in membrane bioreactors: assessment of different strategies for energy saving

Membrane fouling represents one of the major limiting issue for membrane bioreactor (MBR) in the wastewater treatment field. Membrane fouling and high aeration requirement (for inducing shear stress to limit fouling) in MBR systems make the operation of such systems economically demanding due to high energetic costs. Despite several studies on MBR fouling have been performed a comprehensive knowledge on how to reduce membrane fouling and consequently energy saving is still lacking and controversial. The aim of this study is to gain insights on the optimization of the operating conditions in an MBR system. In particular, the influence of the aeration intensity and the durations of filtration and backwashing phase were analyzed in order to optimize the energy saving and effluent quality. To accomplish such goals an integrated MBR model developed and calibrated in previous studies was employed. Monte Carlo simulations were performed for different scenarios each implementing different operating conditions. The results demonstrated that the air flow rate is a key parameter for controlling and reducing the energetic demand and for maintaining a high quality effluent.